kinetics of self-annealing in nanocrystalline electrodeposits

Electrochemical deposition has become the key technology in manufacturing functional thin films with finite structures, e.g. for microsystems and microcomponents. The functionality and reliability of such films depend on their microstructure – however, the thermodynamically non-equilibrium state of as-deposited films causes substantial changes of the microstructure and related properties with time. For copper, which has become the dominant material for interconnects, dramatic microstructure changes due to recovery, recrystallization and grain coarsening have been observed even at room temperature (self-annealing). Electrodeposited nickel, a promising material to realize movable structures for micro-electro-mechanical (MEMS) applications, is well-known for changes of the internal structure at elevated temperatures.
The project will focus on the (self-)annealing behavior of free-standing electrodeposited Cu- and Ni-line patterns. In-situ XRD studies of crystallographic texture and peak analysis with simultaneous monitoring of the electrical resistivity on Cu-line patterns will be supplemented by FEGSEM-EBSD. Ni-line patterns will be investigated similarly with XRD and EBSD after annealing at elevated temperatures. From in-situ synchrotron measurements during isothermal annealing the growth rates of individual grains will be determined. Based on the gathered data (recrystallized volume fraction, grain size distribution, microstrains, texture components) deviations from the processes in deformed bulk metals will be modeled in order to account for the effect of surface, interface and grain boundary energies on the driving force of (self-)annealing in nanocrystalline electrodeposited films.